In the packaging of heat generating electrical components, such as high voltage power supplies, and low voltage power supplies, for example, housings or containers for such components are required that provide the proper dissipation of heat as well as permitting ease of maintenance with respect to the components mounted therein. The problems connected with such heat dissipation, when used in airborne radar type systems, for example, are greatly increased where such housings are subjected to wide excursions of ambient temperature, high levels of vibration, and have limited space requirements.
It is well known that components which generate a moderate amount of heat may be mounted in a metallic container that is surrounded by a gaseous dielectric, such as air, with the heat being transferred to the surrounding air and conducted by the metallic container. For components that generate a much greater degree of heat, a liquid dielectric is necessary for conducting the heat from the components through the metallic housing.
However, when a liquid dielectric coolant is required, volume must be allowed for thermal expansion of the liquid in the container. To partially fill such a housing or container to provide space for the liquid to expand, permits voids in the coolant thereby creating hot spots or electrical breakdown. Heretofore, it has been proposed to provide a housing or container with a voidfree liquid coolant that utilizes a spring loaded bellows connected to the liquid container. The expanding liquid in the container fills the bellows, against the force of the spring, and when the liquid contracts in volume, the spring forces the liquid back into the container. Such an arrangement, although functionally satisfactory for many applications, requires extra space in order to accommodate the external bellows structure. Another solution proposed a housing with a flat flexible bladder forming a portion of the chamber that houses the components, and a pressurized gas, usually air was applied to the opposite surface of the bladder. The pressurized air was usually supplied by the aircraft at a constant pressure, which required external and relatively complicated apparatus, that also tended to frustrate the space limitations.
Thus, it is desirable to provide a heat dissipating container with heat generating components surrounded by a liquid dielectric that is compact and does not require an external structure or apparatus to compensate for the thermal expansion and contraction of the liquid coolant.